Coin testing device for comparing coin to be tested with a standard coin

ABSTRACT

The genuineness of a coin is determined by comparison of the &#39;&#39;&#39;&#39;test&#39;&#39;&#39;&#39; coin with a &#39;&#39;&#39;&#39;standard&#39;&#39;&#39;&#39; coin which are interposed between a primary coil and first and second secondary coils respectively of a transformer, the primary coil being supplied with an AC signal while the secondary coils are connected in series so that the voltages induced by said primary coil are subtracted, and said series connection being coupled to a circuit arrangement which controls a coin gate which allows the test coin to pass into a channel for accepted coins only if the signal delivered by the series connection of the secondary coils does not exceed a threshold value during a test period in which the test coin is in a test position range between the primary and said first secondary coil.

[United States Patent [72] Inventor Adolf HinterstockerHirschbergstrasse 28, Roggersdorf, near Holzkirch'en, Germany [21] Appl.No. 852,531 [22] Filed Aug. 25, 1969 [45] Patented Aug. 17, 1971 [32]Priority Aug. 28, 1968 i 1] Germany [11] ll7747545 [54] COIN TESTINGDEVICE FOR COMPARING COIN TO BE TESTED WITH A STANDARD COIN 9 Claims, 5Drawing Figs.

[52] U.S.Cl 194/100 A, 209/81 A [51 Int. Cl G07f 3/02 [50] Field ofSearch 194/ l 00, 100.5; 209/81, 81.1

[56] References Cited UNITED STATES PATENTS 3,373,856 3/1968 Kusters eta]. 194/100 FOREIGN PATENTS 455,362 l/-1935 Great Britain 194/100Primary ExaminerSamue1 F. Coleman Assistant Examiner-David A. ScherbelAltorney-Spencer & Kaye ABSTRACT: The genuineness of a coin isdetermined by comparison of the test coin with a standard coin which areinterposed between a primary coil and first and second secondary coilsrespectively of a transformer, the primary coil being supplied with anAC signal while the secondary coils are connected in series so that thevoltages induced by said primary coil are subtracted, and said seriesconnection being coupled to a circuit arrangement which controls a coingate which allows the test coin to pass into a channel for acceptedcoins only if the signal delivered by the series connection of thesecondary coils does not exceed a threshold value during a test periodin which the test coin is in a test position range between 3,059,74910/1962 Zinke 194/100 the primary andsaid first secondary coil.

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COIN TESTING DEVICE FOR COMPARING COIN TO BE TESTED WITH A STANDARD COINBACKGROUND OF THE INVENTION It is known to compare a test coin and astandard coin in a bridge circuit comprising a first and a secondinductor into which said test coin and said standard coin are inserted.The bridge compares the impedance of the coils which depend on the coinsdisposed within the respective coils.

SUMMARY OF THE INVENTION It is the main object of the present inventionto provide a coin testing device which is able to discriminate betweengenuine coins and spurious coins or slugs having the same size both ifthe items to be discriminated are made of different metals or alloys,and if the items to be discriminated are made of the same alloy buthaving different coin devices coined thereon. The later case applies,e.g., for the distinction of British one shilling coins and German oneDeutsche Mark coins. This problem which cannot solved with the knowncoin testing devices is solved, as well as others, by a coin testingdevice according an embodiment of the invention comprising a coin chutehaving a coin input end and leading downwards from said end, a coinsensing device providing an electrical output signal when a coin to betested (test coin") travelling through said chute is in a predeterminedposition within said chute, testing means actuated by said electricaloutput signal and comprising an oscillator and a primary coil coupled toan output of said oscillator and positioned adjacent a first side ofsaid coin chute, said primarycoil having an axis extending at leastsubstantially normal to a main plane of said coin chute, a controlcircuit controlled by the output of the test means, an electromagneticrelay actuated by said control circuit and having an armature steeringthe test coin into a channel for accepted coins (go-channel") or achannel for rejected coins (rejectchannel") depending on the result ofthe test, and an energy source for supplying energy for operation of theoscillator, the test means, the control circuit and the relay.

A coin testing device of the above-defined type is characterizedaccording to the invention by first and second secondary coils, thefirst secondary coil being positioned essentially coaxial to the primarycoil adjacent to the coin chute and on the opposite side thereof withrespect to the primary coil, said second secondary coil being positionedessentially coaxially to said primary coil at an end thereof which isopposite to the end adjacent to said first secondary coil, said firstand second secondary coils having essentially the same size and numberof turns, further by means for supporting a typical specimen of thecoins to be accepted (normal coin) between said primary coil and saidsecond secondary coil, means for connecting the circuits of the firstand second secondary coils in series so that voltages which are inducedby the primary coil in the first and second secondary coils are insubtracting relationship, a threshold and amplifier circuit provided insaid control circuit for activating said coin sensing device during ashort period of time (test period") during which test period the testcoin is within a test range between said primary coil and said firstsecondary coil, said control circuit actuating said relay only if anoutput signal provided by said series connection during said test perioddoes not exceed a predetermined threshold value during any time of saidtest period, and stop or gate means actuated or formed by the armatureof said relay, adapted to extend into said coin chute, and steering saidtest coin into the reject channel when said relay is deenergized whileallowing the test coin to travel into said go-channel when said relay isenergized.

A mechanical coin-testing device or slug rejector is preferably providedbetween said input end of said coin chute and the coin testing deviceaccording to the invention, said mechanical device being constructed topass only coins the diameters and thicknesses of which falling intonarrow ranges.

The capability of the present coin testing device to reject slugs andspecially designed counterfeits is thereby greatly increased.

Further objects, features and advantages of the present invention willbecome more apparent if the following is taken in view oftheaccompanying drawings of which:

FIG. 1 is a schematic circuit diagram of a coin testing device accordingto a preferred embodiment of the invention;

FIG. 2 is a schematic front view (front cover and first secondary coilremoved, and partly broken away) of the mechanical portion of theembodiment according to FIG. 1;

FIG. 3 is a schematic circuit diagram of the electrical portion of thecoin-sensing device;

FIG. 4 is a circuit diagram of an oscillator for a somewhat modifiedembodiment similar to FIG. 1 and FIG. 5 a circuit diagram of anoscillator for another modification ofFIG. 1.

Referring now to FIGS. 1 to 3, there is illustrated a preferredembodiment of the invention comprising a coin chute 10 into which thecoins to be tested (test-coins) are inserted through a coin input slot12. A mechanical slug rejector 14 is provided behind slot 12. Thisslug-rejector may be of a known type, e.g., a ledge-type slug rejectorwhich allows to pass only coins the width and diameter of which lying innarrow ranges. The coin chute 10 emerging from the mechanicalslugrejector 14 passes between a primary coil 18 and a first secondarycoil 20. At least in this area the coin chute consists of anelectrically nonconducting material-or is provided with appropriateopenings so that the induction field between coils l8 and 20 is notdisturbed.

Primary coil 18 is connected to output terminals of an oscillator 22which delivers an alternating current to coil 18, said AC current havinga frequency preferably between about 30 and kc./sec. An electronicvoltage regulator 24 supplies regulated electrical energy to oscillator22. An energy source 28 which may comprise a battery is connected by aswitching device 26 to the input of energy source 28. The switchingdevice 26 comprises a normally open contact 29 (FIG. 3) of anelectromechanical relay 62 (FIG. 3) which contact is closed under thecontrol of the coin sensing device 16 for a short period of time (testperiod) when the test coin 30 travelling through coin chute 10 isbetween coils 18 and 20. The test period is sufficiently short, eg,about a hundredth of a second, so that the position of the test coin 30which is moving continuously through coin chute 10 does not varyappreciably during the test period.

A second secondary coil 32 is provided coaxial to primary coil 18 on aside thereof which is opposite to first secondary coil 20. Secondarycoils 20 and 32 are at least essentially symmetrically disposed inrespect to primary coil 18. Means are provided to connect the circuitsof secondary coils 20 and 32 in series so that the voltages induced byprimary coil 18 in the secondary coils 20 and 32 are in opposite,subtracting relationship. Preferably, coils 20 and 32 are directlyconnected in a series circuit which is coupled to an input of anamplifier circuit 34 which provides an amplified output signal to afullwave rectifier circuit 36 which in turn provides a rectified voltageto the input of a Schmitt-trigger circuit 38. Schmitttrigger circuit isactivated if and when the output of the fullwave rectifier exceeds apredetermined threshold value. This means that Schmitt-trigger circuit38 is actuated if the output signal provided by the series circuit 20,32 exceeds a predetermined value.

The output of Schmitt-trigger circuit 38 is coupled to an input of aninverter amplifier and holding circuit 40. Circuit 40 produces an outputsignal only if Schmitt-trigger circuit 38 has not been triggered at anytime during the entire test period. The output signal of circuit 40activates a power amplifier 44 controlling an electromagnetical relay 42the drop out of which being delayed. Relay 44 comprises an armature 46which forms or controls a chute gate. Chute gate prevents when relay 44is deenergized passing of the test coin from coin chute 10 into go-chute10a and directs the test coin into a reject chute 10b while the testcoin is allowed to pass into the gochute 10a when relay 44 is energized.

Means 48 are provided for positioning between primary coil 18 and secondsecondary coil 32 a typical specimen 50 of the coins to be accepted.

A preferred embodiment of coin-sensing device 16 is shown in FIG. 2. Thecoin-sensing device shown in FIG. 2 comprises a lever 54 having threearms 54a, 54b and 540. Lever 54 is pivotally supported by a pin 52. Arms54a and 54b are lying at the lower edge of coin chute 10 so that testcoin 30 moving through chute 10 from the right to the left side in FIG.2 is straddled by arms 54a and 54b. Lever S4 is then pivoted in acounterclockwise direction by the weight and impetus of coin 30 into aposition shown in dashed lines. The test coin assumes a position 30between primary coil 18 and first secondary coil 20 when lever 54 is inthe actuated position shown in dashed lines (FIG. 2). Only primary coil18 is schematically shown in FIG. 2, first secondary coil 20 would beabove the paper in FIG. 2 and attached into a cover member not shownwhich is hinged to the base member of the device which is partiallyshown in FIG 2. A small permanent magnet 56 is fixed to the end of thethird arm 540 of lever 54, said permanent magnet 56 lying adjacent areed-contact switch 60 when lever 54 is in the actuated position.

Reed-contact switch 60 comprises a normally open contact which is closedby the magnetic field produced by permanent magnet 56. The normally opencontact of the reed-contact switch 60 is arranged in a series circuitconnected between the live and ground terminals of energy source 28 andcomprises further a driving coil of electromagnetic relay 62 and aparallel combination 64 of a capacitor and resistor. The capacitor ofthe parallel combination 64 is charged when reed-contact switch 60 isclosed and the charging current energizes relay 62 for a predeterminedperiod of time namely the test period.

Operation of the described embodiment of the present invention is asfollows. When the test coin moving through coin chute l arrives at thecoin-sensing device 16 and actuates lever 54 switch 28 closes for abouta hundredth of a second. Hereby oscillator 22, amplifier 34,Schmitt-trigger circuit 38 and circuit 40 are provided with electricalenergy from energy source 28 and activated. Oscillator 22 delivers analternating current to primary coil 18 during the test period duringwhich switch 28 remains closed. The position of the test coin betweencoils l8 and 20 does not change appreciably during the test period. Avoltage is produced at the input of amplifier 34 and Schmitt-triggercircuit 38 respectively which does not exceed the threshold value duringthe test period if the test coin 30 is identical with standard coin 50within given limits which may be varied by adjusting of Schmitt-triggercircuit 38. Power amplifier 42 is switched on by circuit 40 ifSchmitttrigger circuit 38 has not been triggered during the test period,and relay 44 is energized and remains energized because of the delayeddropout until the test coin has passed into gochute 100.

However, Schmitt-trigger circuit 38 is triggered if coin 30 is notsimilar to standard coin 50, and then circuit 40 does not provide anoutput signal for activating power amplifier. Relay 44 remainsdeenergized, the test coin is recoiled by armature 46 which forms a stopextending into the path of the test coin, and test coin is directed intothe reject chute b as indicated by the dotted arrow in FIG. 2.

According to a further aspect of the present invention, thediscrimination capability of the present coin testing device is greatlyimproved by varying, during the test period, a parameter selected fromthe group of signal amplitude and signal frequency. ofthe signal whichis supplied to primary coil 18 by oscillator 22. This may beaccomplished by modified oscillator means 22' and 22" shown in FIGS. 4and 5 respectively. Oscillator means 22, 22" may be used as oscillator22 in FIG. 1 or a portion thereof (e.g., in combination with a followingbuffer stage not shown).

Referring to FIG. 4 there is shown an oscillator 21 comprising a knowntransistor oscillator circuit having a frequencydetermining parallelresonant or tank circuit 70. A series circuit comprising an additionalcapacitor 72 and a transistor switch 74 is connected across tank circuit70. An input electrode (base electrode) of transistor 74 is coupled toan astable multivibrator circuit 76. Both the oscillator section and themultivibrator section of oscillator 22' are provided with energy fromenergy source 28 for operation during the test period and multivibrator76 delivers to transistor 74 a square wave signal by which capacitor 72is connected in parallel to tank circuit 70 and disconnected from tankcircuit once or a number of times during the test period. The frequencyof the output signal of oscillator 22' is switched thereby between twovalues once or a number of times during the test period.

The oscillator portion of oscillator 22 comprises a transistor 82 theemitter of which being coupled to ground by an emitter impedance 80which is, according to a further feature of the invention, a temperaturedependent resistor which is heated by the emitter current of transistor82 so that the resistance, the degenerative effect of emitter impedanceand thus the signal amplitude are varied during the test period. Theoutput signal of oscillator 22' may be derived from output terminal 78.

Oscillator 22" shown in FIG. 5 produces an output signal the frequencyof which varies continuously during the test period. Oscillator 22"which may be of known construction and is shown schematically in blockform comprises a frequency determining tank circuit 70. A series circuitcomprising a coupling capacitor 81 and a varactor diode 83 is connectedacross tank circuit 70. The junction of capacitor 81 and diode 83 iscoupled through an isolation impedance 84 to a capacitor 86. Capacitor86 is charged through a resistor 88 upon closing of relay contact 28whereby the bias of the diode 83 and the frequency of the oscillatorsignal are varied. Tank circuit 70' may be part ofa beat-frequencyoscillator circuit. Resistor 90 connected in parallel to capacitor 86provides for discharging of capacitor 86 after opening of contact 28 atthe end ofthe test period.

The circuits mentioned above and shown in block form or schematicallyare preferably transistorized circuits which may be of knownconstruction.

As various changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

lclaim:

1. A coin-testing device comprising a coin chute, a coinsensing deviceproducing an electrical output signal when a coin to be testedtravelling through said chute is in a predetermined position within saidchute; testing means actuated by said electrical output signal andcomprising an oscillator and a primary coil which is coupled to anoutput of said oscillator and positioned adjacent a first side of saidcoin chute, said primary coil having an axis extending substantiallynormal to a plane comprising said coin chute; a control circuitresponsive to the output signal of said testing means; a relay actuatedby said control circuit and having an armature steering the test coininto a chute for accepted coins or a chute for rejected coins dependingon the result of the test, and an energy source for providing energy foroperation of the oscillator; the testing means and the control circuitcharacterized by first and second secondary coils, the first secondarycoil being positioned essentially coaxial to the primary coil adjacentto the coin chute and on the opposite side thereof with respect to theprimary coil, said secondary coil being positioned essentially coaxiallyto said primary coil at an end thereof which is opposite to the endadjacent to said first secondary coil, said first and second secondarycoils having essentially the same size and number of turns; further bymeans for supporting atypical specimen of the coins to be acceptedbetween said primary coil and said second secondary coil, means forconnecting the circuits of the first and second secondary coils inseries to form a series circuit so that voltages which are induced bythe primary coil in the first and second secondary coils are insubtracting relationship; a threshold and amplifier circuit provided insaid control circuit for activating said coin-sensing device during ashort period of time (test period) during which the test coin is withina test range between said primary coil and said first secondary coil;said amplifier circuit actuating said relay if the signal produced bysaid series circuit and coupled to said threshold circuit does notexceed a predetermined value at any point of time during the testperiod; and stop or gate means actuated or formed by an armature of saidrelay, which means extending into said coin chute and directing thetested coin into the reject channel when said relay is deenergized whilesaid means allow the test coin to pass into the channel for acceptedcoins when the relay is energized.

2. The device defined in claim 1 characterized in that said coin sensingdevice comprises switching means for connecting said energy source tosaid oscillator and control circuits during the test period.

3. The device defined in claim 2 characterized in that said switchingmeans comprises a pivotally supported lever having three arms, two ofwhich being positioned in vicinity of said coin chute so that a coinmoving through said chute is straddled by said arms and pivots saidlever; that a magnet body is attached to the third arm, and that areed-contact switch is provided at a position adjacent which the magnetbody is positioned in the pivoted state of said lever, said reed-contactswitch being actuated by a magnetic field provided by said magnet body.

4. The device defined in claim 1 characterized by means for changing atleast one parameter including signal amplitude and signal frequency, ofthe signal supplied by said oscillator to said primary coil during thetest period. t

5. The device defined in claim 4 wherein said means is adapted to switchthe oscillator frequency between two values during the test period.

6. The device defined in claim 4 wherein said means is adapted to varythe oscillator frequency continuously during the test period.

7. The device defined in claim 4 wherein said means varies the signalamplitude. v

8. The device defined in claim 1 characterized by a mechanical slugrejector provided in the path of the test coin between the input end andthe area between the primary and first secondary coils, said rejectorbeing adapted only to pass coins the diameter and thickness of whichlying in narrow ranges.

' 9. A coin testing device comprising at least one inductor, means forpositioning a coin to be tested in the vicinity of said inductor, meansfor supplying an AC signal to said inductor, means responsive to theeffects of said coin on a signal derived from said inductor, means forguiding the coin into one of several channels according to the effectsof the coin on said signal, and means for varying a parameter includingfrequency and amplitude of the signal supplied to said inductor duringthe period of time during which said means responsive to the effects ofthe coin on said signal is primed to actuate said guiding means.

1. A coin-testing device comprising a coin chute, a coin-sensing deviceproducing an electrical output signal when a coin to be testedtravelling through said chute is in a predetermined position within saidchute; testing means actuated by said electrical output signal andcomprising an oscillator and a primary coil which is coupled to anoutput of said oscillator and positioned adjacent a first side of saidcoin chute, said primary coil having an axis extending substantiallynormal to a plane comprising said coin chute; a control circuitresponsive to the output signal of said testing means; a relay actuatedby said control circuit and having an armature steering the test coininto a chute for accepted coins or a chute for rejected coins dependingon the result of the test, and an energy source for providing energy foroperation of the oscillator; the testing means and the control circuitcharacterized by first and second secondary coils, the first secondarycoil being positioned essentially coaxial to the primary coil adjacentto the coin chute and on the opposite side thereof with respect to theprimary coil, said secondary coil being positioned essentially coaxiallyto said primary coil at an end thereof which is opposite to the endadjacent to said first secondary coil, said first and second secondarycoils having essentially the same size and number of turns; further bymeans for supporting a typical specimen of the coins to be acceptedbetween said primary coil and said second secondary coil, means forconnecting the circuits of the first and second secondary coils inseries to form a series circuit so that voltages which are induced bythe primary coil in the first and second secondary coils are insubtracting relationship; a threshold and amplifier circuit provided insaid control circuit for activating said coin-sensing device during ashort period of time (''''test period'''') during which the test coin iswithin a test range between said primary coil and said first secondarycoil; said amplifier circuit actuating said relay if the signal producedby said series circuit and coupled to said threshold circuit does notexceed a predetermined value at any point of time during the testperiod; and stop or gate means actuated or formed by an armature of saidrelay, which means extending into said coin chute and directing thetested coin into the reject channel when said relay is deenergized whilesaid means allow the test coin to pass into the channel for acceptedcoins when the relay is energized.
 2. The device defined in claim 1characterized in that said coin sensing device comprises switching meansfor connecting said energy source to said oscillator and controlcircuits during the test period.
 3. The device defined in claim 2characterized in that said switching means comprises a pivotallysupported lever having three arms, two of which being positioned invicinity of said coin chute so that a coin moving through said chute isstraddled by said arms and pivots said lever; that a magnet body isattached to the third arm, and that a reed-contact switch is provided ata position adjacent which the magnet body is positioned in the pivotedstate of said lever, said reed-contact switch being actuated by amagnetic field provided by said magnet body.
 4. The device defined inclaim 1 characterized by means for chAnging at least one parameterincluding signal amplitude and signal frequency, of the signal suppliedby said oscillator to said primary coil during the test period.
 5. Thedevice defined in claim 4 wherein said means is adapted to switch theoscillator frequency between two values during the test period.
 6. Thedevice defined in claim 4 wherein said means is adapted to vary theoscillator frequency continuously during the test period.
 7. The devicedefined in claim 4 wherein said means varies the signal amplitude. 8.The device defined in claim 1 characterized by a mechanical slugrejector provided in the path of the test coin between the input end andthe area between the primary and first secondary coils, said rejectorbeing adapted only to pass coins the diameter and thickness of whichlying in narrow ranges.
 9. A coin testing device comprising at least oneinductor, means for positioning a coin to be tested in the vicinity ofsaid inductor, means for supplying an AC signal to said inductor, meansresponsive to the effects of said coin on a signal derived from saidinductor, means for guiding the coin into one of several channelsaccording to the effects of the coin on said signal, and means forvarying a parameter including frequency and amplitude of the signalsupplied to said inductor during the period of time during which saidmeans responsive to the effects of the coin on said signal is primed toactuate said guiding means.